Bag machine

ABSTRACT

The bag machine of the present disclosure is of the type which can produce bags made of various thermoplastic sheet material and can be adapted to make side weld or bottom weld bags. The following description will, however, be confined to the production of side weld bags. A roll of plastic web is mounted on an unwind stand and traverses a folding board constraining the web to fold along its longitudinal median or along a line spaced from and parallel to the longitudinal median in the event it is desired to produce wicketed bags having a lip with a pair of holes in which is inserted a U-shape wire called a wicket. Downstream of the folding board a gusseter is provided to produce a fold which permits greater expansion at the bottom of the bag. The folded and gusseted web thence comes under the influence of a reciprocating transversely disposed seal and cutter bar which divides the web, at longitudinally spaced intervals, to produce individual bags. The bags are then transported to a table which is provided with devices for arranging the bags into a stack.

[is] 3,678,813 July 25, 1972 United States Patent Wech [54] BAG MACHINEABSTRACT [72] Inventor: Robert-J. Wech, Pinecrest Road, RR. 5, GreenBay, Wis. 54303 plastic sheet materiwe Mi t 0 t dd e m mn n w .m e b r eV e w 0 in w n .w t D.

& 1 o N production of side weld bags.

Related U.S. Application Data Division of Ser. No. 760,048, Sept. 16,i968.

d and A roll of plastic web is mounted on an unwind stan traverses afolding board constrainin g the web to fold along its FieldofSearclii............::::::::::::..........

II- C I n .l. .111] 2 8 555 [[i folding board a gusseter is provided toproduce a fold which permits greater expansion at the bottom of the bag.The folded and gusseted web thence comes under the influence of :1

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INVENTOR. ROBERT .1 weca ATTORNEYS BACKGROUND OF THE INVENTION In orderto attain a production rate of 200 or more quality thermoplastic bagsper minute it is essential to design the bag making machine withfeatures that provide: (a) positive control of the film during itsunwinding from the parent roll; (b) maintenance of a fixed positionalrelationship between the parent roll supporting stand and the infeedframe of the baging machine; when desired, a gusseting mechanism whichprovides a minimum drag to the film while insuring a gusset of constantdepth; (d) web draw rolls whose nip pressure is evenly distributed andhas the ability to apply a differential nip pressure from one end of therolls to the other; (e) mechanism which will release the nip pressure inthe event film movement is stopped to prevent the creation of flat spotson the film; (f) a seal bar which will maintain a uniform evenlydistributed temperature throughout its length and one that is shieldedto prevent heat loss to the film; (g) a seal bar drive arranged for amanual or automatic lift when desired or when web feeding is interruptedfor any reason; (h) mechanisms to vary the length of the bag beingproduced while the machine is operating to correct or change the size ofthe bags accurately under operating conditions with no down time and;(i) a bag transporting conveyor, which conventionally runs at higherspeed than the film, including an easily adjustable positive controlarrangement whereby adjustments can be made under operating conditionsto insure that the trailing end of the bag is engaged by a conventionalbag slow down mechanism to stack the bags so that their margins are inregistration.

SUMMARY OF THE INVENTION The present application is concerned with theprovision of a gusseting mechanism which makes a gusset of constantdepth,

. is rapidly adjustable to change the depth of the gusset and is movabletransversely in the event it is desired to change the path of the filmrelative to the longitudinal median of the bag machine. To achieve suchflexibility it is preferable, if not essential, that the gusseter bemounted at a place where the speed of the web is substantially constantso as to obviate the problems of uneven gusset depth due to film bounce.To fulfill this condition the gusseter of the present invention ismounted between the folding board and the infeed frame of the bagmachine. The construction of the gusseting attachment is designed sothat an operator can rapidly and easily adjust the gusseter to producegussets of a wide range of depth and it also has the ability to reduce,to an absolute minimum, drag imposed on the film thereby reducing thenip pressure of the web feeding rolls. The gusseter is also designed tofacilitate threading of a new roll of film into the machine. This isdesirably accomplished by moving the gusset forming wheel out ofcontract with the film.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. IA and IB, when viewed togetheralong the break line R show the bag machine of the present invention inlongitudinal section wherein the path of the web is shown by a brokenline and the direction of web feed is indicated by arrows appliedthereto.

FIG. 8 is a partial section, on enlarged scale, taken along the line 88of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Arrangement Withreference to FIGS. IA, IB, 2A and 2B it will be noted that the bagmachine of the present invention is generally indicated by the numeral20 and it comprises an unwind stand 22 (FIG. 2A) rotatably supportingcore shafts 24 which in turn support film rolls 26. The web, designatedby the letter W, unwound from the roll 26 is folded along a lineparallel to its ends by a folding board or a V-board 28. When so calledeven edged bags are made the fold line is located at the longitudinalmedian of the web while the fold line for lipped bags is spaced from andparallel to the longitudinal median. FIG. 2A shows the V-board set upfor producing lipped bags since the left hand margin of the web,identified by L. H., is laterally spaced from the right hand margin R.H. downstream from the V- board 28. The web then comes under theinfluence of a gusseting mechanism 30 which forms an inwardly directedfold on that portion of the web which defines the bottom of thecompleted bag. The fold is shown by a dotted line in FIG. 2A and isidentified by numeral 32.

Referring to FIG. IA it will be seen that the gusseting mechanism 30 ismounted on support arms 34 pivotally connected to a transverse rod 36mounted to and extending between laterally spaced infeed frame members38. Rotatably supported on the transverse rod 36 is a roller 40 whichdirects the web between a first set of infeed rolls of 42 connected toconventional nip pressure regulating means 43. The web is thence trainedabout a plurality of idler rollers 44, mounted on dancer arms 46, androllers 48 extending between and rotatably mounted on the infeed framemembers 38. The length of web accumulated in the path defined by therollers 44 and 48 serves to provide a temporary supply whichautomatically increases or decreases in response to transient values ofweb tension. This arrangement tends to produce a constant value of webtension.

The bag machine frame comprises a base plate 50 having mounted thereontransversely spaced upwardly projecting side frame members 52 locatedsubstantially at the midportion of the machine. At the discharge end,outfeed frame members 54 are also mounted on the base plate 50 andserved to support bag discharge control devices explained in detailhereinafter.

Referring again to FIG. IA it will be observed that between the infeedframe members 38 and the mid-frame members 52 a horizontal accessoryplatform 56 is connected therebetween and it serves to support holepunching assemblies 58 mounted on a base plate 60. As shown in FIG. 2Bthe base plate 60 is mounted on a rectangular frame 62 and istransversely adjustable on this frame. It is held in a selectedtransverse position by a lock screw 64. Longitudinal adjustment of therectangular frame 62 carrying the hole punch assemblies 58 isaccomplished by racks 66 and pinions 68. As shown diagrammatically inFIG. 2B the racks 66 are fixed to the inner surfaces of the side rails56 while the pinions 68 are keyed to a transversely extending shaft 70rotatably mounted in the rectangular frame 62. On one end of the shaft70 a knob 71 is keyed for rotating the shaft 70 and consequentlyadjusting the longitudinal position of the hole punching assemblies 58.

Downstream of the hole punching assemblies 58 an electronic webregistration device 72 commonly referred to as a scanner, is likewisemounted for longitudinal and transverse adjustment. Longitudinaladjustment is accomplished by pinions 74 (FIG. IA) in mesh with theracks 66. The pinions 74 are mounted on a transverse shaft 76 rotatablycarried in generally L-shaped in frames 78. On the upright legs of the Lframes 78 a transverse bar 79 is secured. Slidably mounted on the bar 79is the scanner 72 which can be locked in any transverse position by alock screw 80. On the horizontal leg of the L frame 78 a transverse bar82 is mounted and it will be observed, by inspection of FIG. 1A, thatits upper surface is in substantially the same plane as the web line. Inorder to insure repeated response of the scanner the upper surface ofthe transverse bar 82 is white in color so as to provide good contrastfor detection of the printed registration mark. As is conventional thescanner is electrically connected to the control circuit of the bagmachine to deenergize the clutch and simultaneously energize the brakethereby arresting the movement of the web for a sufficient period oftime to allow the transverse seal bar to operate and thereby make theside weld for two longitudinally adjacent bags. After the seal barcompletes its function the control circuit is then conditioned torelease the brake and engage the clutch commencing web movement.

As shown in FIG. 1B upstream of the scanner the web passes betweenintermittently operating draw rolls 84 associatedwith upper and lowersets of the stripper fingers 86 and 88, respectively, detachably mountedon transverse bars 90 and 91. The draw rolls are connected, ashereinafter will be more particularly described, with means, generallyindicated by the numeral 92, for controlling the nip pressure the drawrolls exert on the film and for removing the nip pressure when required,either selectively or automatically.

To resist the deflection of the draw rolls, particularly at theirmidportion and thereby insure an even value of nip pressure along thelength of the draw rolls, a back-up roll 94, in rolling contact with thelower draw roll, is provided. The backup roll 94 is rotatably mounted ina yoke 96 having a link extension 98 which forms one link of a parallellinkage mechanism 100. The vertical position of the back-up roll 94 andaccordingly the back-up force it will apply to the draw rolls 84 can beselected by adjusting a screw jack 102.

Immediately downstream of the draw rolls there is provided a verticallyreciprocating sealing mechanism 104, cooperating with an intermittentlyrotating seal roll 106 for making the transverse seals in the foldedweb. These seals constitute the lateral margins of the bags. The sealmechanism is reciprocated by a pair of cams 108 (one of which is shownin FIG. 1B) keyed to a shaft 110.

After the web passes the seal mechanism individual bags are at that timeproduced and they are received by a continuously operating belt conveyor112. The index conveyor comprises a series of transversely spaced andaligned upper and lower sets of belts 114 and 116, respectively, movingin a direction indicated by the arrows in FIG. 18, Those reaches of thebelts which are traveling from left to right, as viewed in FIG. 1B, arein contact for the purpose of gripping the bags discharged from thesealing mechanism and transporting them to a stacking table 118 providedwith adjustable stop plates 120 for collecting the bags in a stack.

The upper belts 114 of the index conveyor 112 pass around an idler shaft122 rotatably supported on linkages 124 mounting a cam follower roller126 which is held in engagement with a cam 128 by a spring 130. As shownin FIG. 1B the cam 128 is mounted on a shaft 132 and during operationthe linkages 124 are oscillated raising and lowering the idler shaft 122which serves the purpose of accommodating any over travel of the bags asthey issue from the sealing and cutting mechanism 104 and thus preventwrinkling of the bag.

Before the bags are discharged to the stacking table 118 they come underthe influence of conventional corrugating rollers 134 which serve tostiffen the bag in the direction of movement so as to prevent distortionthereof as it is ejected to the stacking table 118. Before beingdischarged to the stacking table the trailing end of the bag ismomentarily gripped by a slow down mechanism 136 of known construction.

In order to synchronize the speed of the belt conveyor so that bagsdischarged therefrom are momentarily gripped at or adjacenttheirtrailing edge, an electrically adjustable direct current drivearrangement 138 (FIG. 1B) is provided. The drive 138 includes a DCmotor, belt and pulley, not shown, for driving a shaft 143. The shaft143 has an adjustable pitch pulley 144 at its opposite end which drivesa belt 145 trained about a pulley 146 mounted on a shaft 147. The shaft147 provides power for the corrugating rollers 134. To drive the indexconveyor 112, a belt and pulley drive train, not shown, transmits powerfrom the shaft 143 to the upper index conveyor drive roller which isadjacent the lower set of corrugating rollers 134. For purposes ofadjusting the pitch of the adjustable pulley 144, a tightener pulley 148tensions the belt and is carried by a stub shaft 150 mounted on anadjustable arm I52.

Gusseting Mechanism The gusseting mechanism 30, generally referred to inthe above described general arrangement, is shown in greater detail inFIGS. 3 through 8. Referring first to FIG. 3, which shows an enlargedperspective of this mechanism, it will be seen that the gussetingmechanism is supported on the arms 34 by rails 184 and 186 rotatablycarrying a shaft 188 having keyed thereon pinions I90 and 192. Thepinions are in mesh with racks 194,196 fixed to the inner verticalsurfaces of the support arms 34. The pinions 190, 192 are held in placeon the shaft 188 by collars 198. The shaft 188 has a threaded extensionbeyond the rail 186 and has threadedly mounted thereon a jam nut 200,serving to lock the shaft against rotation, and a hand wheel 202 securedto the shaft 188 for effecting rotation thereof to thereby causelongitudinal translation of the gusseter mechanism 30 whenever the shaft188 is rotated.

Rigidly attached to the upper surface of the rails 184 and 186 is asupport plate 204 provided with a slot 206. The support plate 204 hasattached thereto a mounting bracket generally indicated by the numeral208 for rotatably supporting a gusseter wheel 210 which, when in itsoperative position is located between stationary gusseter plates 212 and214, the upper and lower plate respectively. These plates are rigidlyfastened to a laterally adjustable support bar 216 overlying and spacedfrom a lower support bar 218 by a spacer block 220.

The gusseter mounting bracket 208 is shown in side elevation in FIG. 7and reference to this Figure will show that the bracket comprises anelongate rectangular bar 222 secured to the support bar 218 by bolt 224having slidably fitted thereon a bushing 226 which is received in theslot 206 and is dimensioned to provide a sliding fit. As will be evidentby inspection of FIGS. 3 and 4 it will be seen that the bar 222 extendssub stantially normal to the support plate 204 and adjacent its outboard end it is tapped to threadedly receive a pivot bolt 228 passingthrough a boss 230 of an arm 232 rotatably mounting the gusseter wheel210 on a small flat head screw 234.

Also projecting from the boss 230 is a lug 236 carrying a pin 238 havinga spring biased ball 240 mounted in a retaining sleeve 242. As shown inFIG. 4 the rectangular bar 222 has a spherically shaped depression 244located to receive the spring biased ball 240 when the gusseting wheel210 is moved to the phantom outlined position shown in FIG. 4. Thisholds the gusseting wheel in that position and-its main purpose is tofacilitate threading of the film through the gusseter. Prior torepositioning the wheel for gusseting, hand folding of that portion ofthe film adjacent the plates 212 and 214 can be done beforethe wheel 210is located between the gusseting plates 212 and 214.

The gusset forming members, that is the plates 212, 214, and thegusseting wheel 210, are arranged so that they can be locatedtransversely relative to the longitudinal median of the bag machine.Such an adjustment is required when it is desired to produce bags ofdifferent length. For example if the film roll on the unwind stand is 24inches wide the maximum length of a non-gusseted bag would be half thatlength or 12 inches; while a gusseted bag made from the same film rollwould be reduced in length by the amount used for the gusset. In theevent film of greater width is used in order to produce gusseted bags ofgreater length it would be necessary to move the gusseting wheels 210and the gusseting plates 212 and 214 to the right, as viewed in FIG. 3.For this purpose a clamping arrangement 246 is provided. With particularreference to FIGS. 3 and 6 it will be observed that the clamp 246comprises a generally U-shaped base member 248 rigidly attached to thesupport plate 204 by fasteners 250. The base member 248 is formed sothat the support bar 218 slidably fits in the generally rectangularspace defined by the base member 248 and the plate 204 (FIG. 6).Disposed above the base member 248 there is a clamping bar 252 having aclearance hole adjacent one end through which is disposed a bolt 254threaded into the base member 248. On the other end of the bar anotherclearance hole is provided having disposed therein a stud 256 alsothreaded into the base member 248 and provided with a knob 257. At theintermediate portion of the clamping bar 252 a set screw 258 is threadedtherein. bearing on the upper surface of the bar 216, and is inforceable contact therewith when the stud 256 is tightened. This, ofcourse, locks the bars 216 and 218 in place and accordingly maintainsthe lateral position of the gusseting wheel 210 and the gusseting plates212 and 214 since they are mounted, respectively, to the bar 218 and thebar 216. In view of the above it will be apparent that when it isdesired to change the lateral position of the gusseting wheel 210 andthe plates 212 and 214 all that is necessary is to loosen the stud 256sufiicient to remove the force supplied by the set screw 258 to the bar216. The desired position of the gusseting mechanism can then beachieved manually by pushing or pulling the interconnected bars 216 and218.

In order to accommodate the gusseter mechanism 30 to the machiningcharacteristics of the film and to prevent damage to the film in theevent portions of the film exhibit more or less resistance to formation,the gusseter wheel 210 is held in its operative position between theplates 212 and 214 by a spring 260. As shown on FIG. 7 one end of thespring 260 is attached to a hook 262 having a threaded stem threadedinto the arm 232. The hook 262 is held against rotation by ajam nut 264.The other end of the spring 260 is attached to a bead-chain 266 whichextends beyond a catch 268 mounted on a bracket 270. As will be observedby reference to FIG. 6 the catch 268 is formed with two upwardlyextending fingers which fit between adjacent beads of the chain 266. Onthe remaining end of the chain 266 a ring 272 is secured which serves tofacilitate grasping of the chain and consequent tensioning of the spring260 to the degree required by the forming characteristics of the film.When a desired degree of tension is achieved, usually determined byobserving film formation while the machine is running, the chain isinserted between the upwardly extending pins of the catch 268.Accordingly it will be seen that by utilizing the spring 260 for urgingthe gusseter wheel 210 between the plates 212 and 214 the gusseter hasthe ability to give in the event increased resistance is encounteredconsequently preventing damage to the film.

Another and further novel feature of the gusseter mechanism pertains tothe general configuration of the gusseter plates 212 and 214. As will beobserved these plates are generally rectangular in configuration and aremade arcuate at the intersection of the margins. As is known by thoseskilled in the art, regardless of their design, gusseting attachmentswear rather rapidly even though surface preparations such as Teflon areapplied to those portions of the gusset forming members which come incontact with the film. While the gusseting mechanism of the presentinvention reduces the wear to an absolute minimum, particularly on thegusseting wheel 210 since it is mounted for rotation thereby obviatingor minimizing relative velocity between the gusseting wheel 210 and thefilm, the gusseting plates 212 and 214 do encounter an appreciableamount of friction and thus are subject to wear. As shown in FIG. 8 thefilm encountering edges of the gusseting plates 212 and 214 areidentified as 212a and 214a respectively. The plates 212 and 214 areprovided with an auxiliary set of mounting holes, collectivelyidentified by the numeral 278 (see FIG. 4) which correspond to thespacing of the mounting holes containing the screws 280. When the edges212a and 214a are worn to the extent that the gusseting function isimpaired the plates 212 and 214 are removed and are repositioned on thesupport bar 216 locating edges 21212 and 214b to make contact with thefilm and thus cooperate with the gussetin wheel 210 to form gussets.

hile the above arrangement of reversing the plates to use opposedmargins of the plates 212 and 214 to extend their useful life, it iswithin the scope of this invention to form the plates so that all fouredges may be used.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention as set forth in theappended claims.

1 claim:

1. An apparatus for making thin thermoplastic bags from an elongatefolded web comprising means for supplying such web folded along a lineintermediate its edges, means for accumulating a quantity of the foldedweb and for imposing a desired tension to the web, means forintermittently pulling the web from said accumulating means whilecausing the web to be withdrawn from said supply means at substantiallya constant rate, means located between said web supply means and saidaccumulating means, for forming a gusset at the folded margin of theweb.

2. The apparatus of claim 1 wherein said gusset forming means comprisescooperating gusset forming members mounted on a frame which is movablerelative to the longitudinal median of bag making apparatus.

3. The apparatus according to claim 1 wherein said gusset forming meansincludes vertically spaced rigidly mounted stationary plates havinglocated therebetween a rotatable wheel resiliently biased between saidplates.

4. The apparatus according to claim 3 wherein said plates are providedwith at least one set of additional mounting holes so that they may berepositioned on the support therefor to present unworn plate margins toengage the moving web.

5. The apparatus according to claim 3 further comprising means mountingsaid rotatable wheel for pivotal movement toward and away from saidplates, and means for holding said wheel away from said plates tofacilitate threading of a new roll web through said gusset formingmeans.

6. The apparatus according to claim 5 wherein said wheel mounting meansis connected to a spring which is arranged to impart a selected preloadto said wheel dictated by the depth of the gusset desired and themachinability of the web.

1. An apparatus for making thin thermoplastic bags from an elongatefolded web comprising means for supplying such web folded along a lineintermediate its edges, means for accumulating a quantity of the foldedweb and for imposing a desired tension to the web, means forintermittently pulling the web from said accumulating means whilecausing the web to be withdrawn from said supply means at substantiallya constant rate, means located between said web supply means and saidaccumulating means, for forming a gusset at the folded margin of theweb.
 2. The apparatus of claim 1 wherein said gusset forming meanscomprises cooperating gusset forming members mounted on a frame which ismovable relative to the longitudinal median of bag making apparatus. 3.The apparatus according to claim 1 wherein said gusset forming meansincludes vertically spaced rigidly mounted stationary plates havinglocated therebetween a rotatable wheel resilieNtly biased between saidplates.
 4. The apparatus according to claim 3 wherein said plates areprovided with at least one set of additional mounting holes so that theymay be repositioned on the support therefor to present unworn platemargins to engage the moving web.
 5. The apparatus according to claim 3further comprising means mounting said rotatable wheel for pivotalmovement toward and away from said plates, and means for holding saidwheel away from said plates to facilitate threading of a new roll webthrough said gusset forming means.
 6. The apparatus according to claim 5wherein said wheel mounting means is connected to a spring which isarranged to impart a selected preload to said wheel dictated by thedepth of the gusset desired and the machinability of the web.